1. Field of the Invention
The present invention relates to a method for controlling a motor roller, which is powered by a brushless motor equipped with a brake mechanism. Such a motor roller is effectively used for a conveyor, in particular, a conveyor that is repeatedly switched on and off.
2. Prior Art
A motor roller for a conveyor is usually stopped by an electric brake. What is stopped, however, is only the rotation of the motor roller itself. The conveyor itself can be moved easily by an external force, etc. On the other hand, in a mechanism in which the conveyor is stopped mechanically using an electromagnetic brake only, the brake pad is subjected to friction, which causes abrasion and shortens the life of the brake pad. In order to solve these problems, a number of methods have been devised to increase the electric brake power. Another method that has been devised for ensuring the stopping position uses both an electric inverter brake and a physical electromagnetic brake. In such a conventional method for controlling a motor roller for a conveyor using both an electric brake and an electromagnetic brake, the electric brake and the electromagnetic brake are activated at the same time.
In the conventional method in which an electric brake and an electromagnetic brake are activated at the same time, the electromagnetic brake is activated at high speed. This causes the brake parts to wear out quickly, shortening the life of the motor roller. On the other hand, adding an independent delay circuit in order to delay the activation timing of the electromagnetic brake with respect to the activation of the electric brake increases the cost.
The present invention aims at solving these problems associated with the conventional methods by using a simple method to delay the activation timing of the electromagnetic brake until after the revolution of the brushless motor is reduced, thereby providing an economical motor roller that can be used over an extended period of time because the brake parts wear less.
To achieve the above object, a motor roller powered by a brushless motor is provided with a built-in electromagnetic brake, and a delay circuit is provided in a drive-controlling device for the motor. The delay circuit uses the motor pulse detected by a motor driver. When a stop signal is inputted, the motor pulse rate declines. This decline of the motor pulse rate is detected to activate an electromagnetic brake. Because the motor pulse can be detected by the motor driver, it is sufficient to mount the delay circuit for activating the electromagnetic brake on the driver substrate of the motor driver; there is no need to provide a special delay circuit device.